An automated test equipment system is used for testing integrated circuit devices or ICs. That testing involves functional testing including time dependent data. The automated test equipment system, also referred to as an ATE tester, typically includes test circuitry that is connected to a control computer. The control computer provides a user interface that accepts and stores functional test patterns and timing data, referred to as test vectors for activating the test circuitry to provide stimulus signals to a device-under-test or DUT. This also includes receiving and evaluating DUT response output signals. The DUT output signals are evaluated to determine the parametric and operational characterization of the DUT. Stored pattern functional testing affords a critical step in the production of integrated circuit devices to provide parametric and operational characterization of the devices.
The present inventor has realized that the effectiveness of such testing relies on accurate synchronization of the tester and DUT. This is because as clock speeds increase to gigahertz and beyond, the effectiveness of the testing is dependent more heavily on precise clock synchronization. At high frequency, inaccuracy of clock and data synchronization can more easily result in false test results because the margins of error decrease as the operating speed of the device under test increases. As discussed below, this may occur because the data transition time or “jitter band” becomes a larger percentage of the data signal, thus creating a larger source of false test results.
What is needed is an apparatus and/or method for ensuring that the response data signal is correctly detected. Thus, it has been determined by the present inventor that what is needed is a means for synchronizing the tester clock signals with incoming DUT response data signals to allow detection of the response data signal away from the jitter band.